Process for production of lubricating oil



April 13,1943 U. B. BRAY ETAL PROCESS FOR PRODUCTION OF LUBRICATING OIL'original Fi1ed Aug. 4,'1931 v muy Y. m W E ma M VE m m@ T Patented Apr.13, 1943 STATES TENT OFFICE PROCESS FOR PRODUCTION OF LUBRICATIN G OILOriginal application Au 555,018. Divided and gust 4, 1931, Serial No.this application February 19, 1935, lSerial No. 7,268

(Cl. ISG-13) 4 Claims.

This invention relates to a method and apparatus for treating petroleumto produce lubricating oil, and is a division of our copendingapplication Serial No. 555,018, iled August 4, Y1931.

`Subject matter disclosed herein but not claimed is claimed in thefollowing copending applications and patents: Serial No. 615,254,1iledAugust 22, 1933 claiming separation of oil into fractions with aselective solvent and/or dewaxing with a selective solvent and adiluent; lSerial No. 709,836, filed February 5, 1934 claiming separationof asphalt from oil at elevated temperature with a liqueed normallygaseous hydrocarbon; Serial No. 9,314, filed March 4, 1935 claimingselective solvent extraction of a partially deasphalted oil; Patent No.1,988,711 claiming deasphalting with solvents followed by solventextraction of the deasphalted oil; Patent No. 1,988,712 claiming`deasphalting and dewaxing with solvents in conjunction with selectivesolvent extraction of the oil; Patent No. 2,006,092' claiming extractionof oil with a selective solvent in the presence of a liquefied normallygaseous hydrocarbon; Patent No. 2,006,093 claiming extraction of oilWith propane and a selective solvent and also extraction of oilcontaining asphalt with a selective solvent and a low boilinghydrocarbon; Patent No. 2,006,- 094 claiming selective solventextraction of an oil in the presence of a liquefied normally gaseoushydrocarbon and dewaxing; Patent No. 2,006,095 claiming dewaxing oil inthe presence of a liqueed normally gaseous hydrocarbon and selectivesolvent extraction of the dewaxed oil; Patent No. 2,006,096 claimingacid treating oil diluted with a liqueiied normally gaseous hydrocarbonand selectivev solvent extraction; and Patent No. 2,006,087 claimingextracting oil with a liquefied normally gaseous hydrocarbon and aselective solvent and acid treating the oil recovered in the liqueednormally gaseous hydrocarbon.

One of the distinctive characteristics of a lubricating oil is itsviscosity. For many purposes lubricants are preferred which exhibit aminimum variation in lviscosity with variations in temperature, i. e.,have low viscosity temperaturev susceptibility. It is generally knownthat the viscosity of lubricating oil produced from Western crude, suchas California naphthene base crudes, lthat is, crude containing asphaltvaries more with change in temperature than do lubricating oils producedfrom paran base crudes. That is, if two such oils have the sameviscosity at 100 F., the Western oil will have a much lower viscosity at210 F. than will the paraliin base-oil. This change in 'viscosity' withtemperature is sometimes called the temperature susceptibility of anoil. It is one of the characteristics of Western lubricating oils thatthey are distillates, that is, are vaporized from crude oil andcondensed. Lubricating oils produced Afrom paraffin base oils,containing substantially no asphalt, are generally produced by rstdistilling lig-ht oils overhead, including the kerosene and gas-oil Aandalso taking overhead light lubricating oils called neutrals having aviscosity in the neighborhood of 10U-200 seconds, Elaybolt -Universalfat100 F., leaving an undistilled residue termed bright stock. The oils ofvarious viscosity are made by blending these neutrals and bright stockin any desired proportion -to obtain the desired viscosity.

It has been observed by one of us that many oils containing asphalt andwax'aremixtures of hydrocarbons analogous both to the `hydrocarbonspresent in parafn base oils and those present in asphalt 'base oils. Ithas further been observed by one of us that during the heating vof anoil containing asphalt, the asphalt apparently induces certain chemicaland perhapscertain physical reactions at relatively low temperatureswhich tend to destroy the linherent low viscosity temperaturesusceptibility of the lubricating oil fractions. This apparent catalyticphenomena seems to explain the observed changes although we do not wishto be understood as being bound by this theory. It has been observedthat these temperatures at which the changes appear Vare below thevaporizing temperatures lin batch distillation (vacuum or steam)ofthelubricatingoil fractions which have Saybolt Universal viscositiesabove 40G-500 seconds at y100 F. Itis Saft to say that no oil containingasphalt'can 'be topped to the point where fractions above 40G-500seconds, Saybolt Universal viscosity Aat 100i F. are vaporized vwithouta degeneration ofthose characteristics of the paraiiin hydrocarbonswhich impart to the cil a low Atempearture viscosity susceptibility.During the distillation of the heavy oils in the presence of asphaltsome change in molecular 4structure orconfiguration takes place whichisa-ttendedbyga Change ofviscosity temperature characteristics. Thisbehavior is thought to be due to pyrolytic reactions which are catalyzedby the presence of asphalt. The above discovery is .made the subjectmatter of application .serial No.' 4,166,189.

In order` to preserve the lnherentcharacteristics of the lubricating oilcomponents vofcrude oil containing asphalt which are impaired by dis--tillatlon methods as previously described. vvWe have, in accordance withthe process of the above application, caused the separation of the oiland Wax from the asphalt by a method wherein the lubricating oilconstituents present in the crude oil are separated from the asphaltpresent in such a manner that the oil retains those characteristicswhich it possessed in the original crude oil. As a means of attainingthis end it has been found advisable to cause the separation of theasphalt from the oil by means of solvents which are capable ofdissolving the oil and which do not dissolve the asphalt. Such solventsare light petroleum fractions, such as naphtha, casinghead gasoline andpetroleum fractions normally vaporous at ordinary temperature andpressure. Other solvents which may be used are alcohol, ether, mixturesof alcohol and ether, acetone, etc. We prefer to use as our solvent apetroleum fraction obtained by the rectification of natural gasoline.For most purposes a fraction composed of 6.72% ethane, 72.2% propane,19.91% iso butane4 and 1.17% normal butane is satisfactory. It will beunderstood, however, that these merely illustrate the type of fractionswhich may be used and that the composition may vary. This fraction willhereinafter be referred to as propane for purposes of simplicity.

In carrying out the extraction of the oil with this light liquidfraction the solution is maintained at a pressure sufficient to maintainthe Y propane liquid at ordinary temperatures. The fraction describedabove is liquid at ordinary temperatures at a pressure of about 125pounds per square inch. The extraction of the oil from the petroleum atsuch pressures results in an asphalt substantially free of oilconsisting chiefly of pure bitumen and a solution of oil and wax in theliquid petroleum fractions. The oil dissolved in the liquid propanecontains substantially all of the lubricating oil components which arepresent in the crude oil and in substantially the same form as theyexist in the original crude oil and also the major portion of the waxpresent in the crude oil.

, We have discovered that many lubricating oils obtained by extractionwith solvents, for instance, propane, from crude oil containing asphaltand 'wax are composed of oils which have a relatively high temperatureviscosity susceptibility and oils -which have a relatively lowtemperature viscosity susceptibility and that these oils may beseparatledinto oils which exhibit a low temperature viscositysusceptibility resembling oils produced from 'non-asphalt containingcrude and oils which exhibit a high temperature viscosity susceptibilitycorresponding to oils produced by distillation. For convenience we willcall the oils which exhibit a low temperature viscosity susceptibilityparainoid and those which exhibit a high temperature viscositysusceptibility and resemble the Western lubricating oil distillatesnon-paraffinoid. The propane extract which consists of such a mixture ofparallinoid and non-paramnoid oils may be separated into theserespective oils by the use of solvent agents which Will selectivelydissolve out the non-parainoid components. We have found that certainsolvents have a selective solvent action for the non-parafnoid oils. Assolvent agents which Will effect this separation We have found liquidsulphur dioxide, mixtures of acetone and benzol, aniline or methylformate useful. Acetone alone, in addition to being an asphaltprecipitant, also has in some measure the ability to split the oil inthe above manner. The use of liquid sulphur dioxide has been foundespecially valuable as a solvent to separate the propane extract intooils which exhibit low temperature viscosity susceptibility and intooils which exhibit high temperature viscosity susceptibility.

As the propane extract from the crude oil consists of a mixture of waxand oil normally solid at ordinary temperatures, it cannot be separatedinto its para'inoid and non-parafnoid components by the use of sulphurdioxide, without considerable difficulty, unless dissolved in a carryingmedium. We have found it advantageous to carry out the extraction of theWax oil mixture with sulphur dioxide in the presence of the liquidpropane used in separating the asphalt. The wax oil mixture is dissolvedin liquid propane after which it is extracted with liquid sulphurdioxide to remove therefrom the non-parallnoid components. The propanesolution of parilianoid oil is then chilled to precipitate the Waxpresent after which the chilled mass is cold settled, centrifuged, orfiltered to separate the wax from the propane solution of oil. Byremoving the sulphur dioxide soluble bodies from the propane solution ofwaxy oil prior to the dewaxing operation we are able to obtain a nalproduct with a lower pour point, i. e., wax content than could beobtained if the sulphur dioxide extraction operation were performedsubsequent to wax removal. The sulphur dioxide removes from oil certainbodies present which are good wax solvents and which have a tendency toprevent precipitation of the Wax during the dewaxing operation.

The propane solution of oil recovered from the dewaxing operationsubstantially free of asphalt and Wax may be further purified bytreatment With sulphuric acid. Such treatment removes from the paraffinoil further impurities which were not removed from the oil by thetreatment with liquid sulphur dioxide.

Generally stated, it is the object of our invention to isolate fromcrude oil those oils having characteristics which impart to it the lowtemperature viscosity susceptibility typical of paraffin base oil.

More particularly, it is an object of our invention to isolate fromasphalt containing oils those components which impart to the oil thereduced susceptibility to change in viscosity with temperature which ischaracteristic of oils obtained from non-asphalt containing oils, thatis, to separate the paraifinoid from the non-paraftlnoid components ofthe asphalt containing crude oils.

It is a further object of our invention to separate asphalt from 4an oilcontaining asphalt, oil and Wax 'by means of a solvent, to separate theWax and paraffinoid oil from the non-paraflinold oil by means of asecond solvent used in the presence of the first solvent, to separatethe Wax from the parainoid oil and thereafter to treat the parafnoid oildissolved in said first solvent with sulphuric acid.

It is a further object of our invention to separate oil and wax from anoil containing asphalt, oil and wax by the use of liquid propane; toseparatethe wax and parainoid oil from the nonparamnoid oil by the useof liquid sulphur dioxide in the presence of liquid propane; to separatethe wax' from the para'inoid oil and thereafter to treat the paraffinoidoil with sulphuric acid.

The figure is one form of apparatus which we may employ to carry out ourprocess.

Referring more particularly to the figure, the crude which has beendistilled to remove Ylight oils'such as gasoline and kerosene and isitself a :residual oil icontaining lubricating fractions, asphalt andwax in' tank I is withdrawn through valve 2 and sent bymeans of pump 3through line: 4 where it meets a stream of liquid propane coming fromtank l through valve II, line I2, pump ||5 and line 2'. ,The mixture oftopped crude and liquid propane passes from line 4 to chiller 5 where aportion of the propane is allowed t0 VaDOTZe through Valve 6 land passesby means of line 1 to pump 32 where it is compressed and sent tocondenser 8 wherel it is liquefied and sent by means of line 9 tostorage tank I0. The vaporization of the propane in chiller 5 causes thetemperature of the mass therein to be lowered. The cool mass fromchiller 5 passes by means of line |3 to agitator I4 where it isthoroughly mixed and sent by means of line I5 to decanter I6 where theasphalt is allowed to settle out.

The asphalt is withdrawn from decanter I6 through valve |1 and sent bymeans of pump I8 through line I9 to heater 20 where the propane andmoisture are vaporized. The heated mass passes from heater through line2| to separator 22 where the asphalt separates from the vapors and iswithdrawn through valve 23 and line 24 in the storage tank 25. Thevapors in separator 22 are withdrawn through line 26 into condenser 21where the water vapor present is condensed. The condensed water andpropane vapor pass into separator 28 where the water separates and iswithdrawn through valve 29 and line 30. Propane vapor passes fromseparator 28 through line 3| to compressor ||3 thence to condenser 8where it is liqueed and passes by means of line 9 to storage tank I0.

The solution of cil in liquid propane in decanter vI6 is withdrawnthrough line 33 and sent to chiller 34. A portion of the propane presentis allowed to vaporize by opening valve and allowing the vapors to passthrough line 36 to compressor |I6 where it is compressed and sent tocondenser 8 and is liquefied, thereafter being sent to storage tank I0.The vapor-ization of the propane in chiller 34 cools the mass which isthereafter withdrawn through valve 31, line 38 and sent by means of pump39 through line 40 to the lower zone of extraction column 4I. Liquidsulphur dioxide from tank 42 is withdrawn through valve 43 and sent bymeans of pump 44 through line 45 to the upper zone of extraction column4|. Due to the difference in specific gravity of the oil introducedthrough the lower zone of the extraction column and the liquid sulphurdioxide introduced into the upper zone of the extraction column, thesetwo liquids tend to separate. As the liquid sulphur dioxide descendsthrough the extraction column it dissolves certain components present inthe oil.

The solution of liquid sulphur dioxide and oil is removed from theextraction column 4I through the valve 46 and sent by means of line 41to vaporizer |05 where the sulphur dioxide is vaporized by 'aid of steamintroduced through closed coil |0| and passes through line |06 tocompressor |01 where it is compressed and sent through line |08 tocondenser |09 where it is liquefied and sent to storage tank 42. Sulphurdioxide free oil in vaporizer |05 is withdrawn through valve |02 andsent through line |03 to tank |04.

The ascending column of oil in extraction column 4I, from which theliquid sulphur dioxide soluble components have been removed, passesthrough valve 48 to line49 to auxiliary separator 50 where any remainingliquid sulphur dioxide is settled out.` A clear solution of oilisiwithdrawn from auxiliary separator v50 through line 52 where it maybe mixed with a further quantity of liquid propane coming from storagetank I0 through Valve 53, pump |I4 and line 54. The solution. of Ioiland propane carrying a small quantity of sulphur dioxide passes intochiller 55 where a' portion of propane is allowed to vaporize by opening4valve 6|. The vaporized propane contaminated with sulphur dioxide,passes through line 62 to compressor where it is compressed and sentthrough line 88 to con denser 89 where both the sulphur dioxide and thepropane are condensed and pass by means of line H0 to separator 90 wherethese two materi-als separate due to their great diilerence in specificgravity. The liquid propane in separator 90 is withdrawn through valve9| and sent by means of pump 93 through line 96 to storage tank I0. Theliquid sulphur dioxide in separator 90 is withdrawn through valve 92 andsent by means of pump 94 `through line 95 to storage tank 42. Thevaporization of the propane in chiller 55 cools the remaining solutionof oil present which passes out through valve 59 and line 51 to pump 58which forces it through lter press 59 where the precipitated wax isremoved through line 60.

The wax-free oil from filter press 59 passes through line 61 where itmeets a stream of sulphuric acid coming from tank 63 through valve 64,line 65 and pump 66. The mixture of acid and oil passes from line 61through agitator 68 where the. massis thoroughly agitated, after whichit passes thro-ugh line 69 to separator 10 where the sludge is allowedto vsettle out. The sludge in separator 10 is withdrawn through valve15, line 16, to pump 'I1 which forces it through line 18 to heater 19where the mass is heated. sufficiently to vaporize the propane present.The heated mass passes from heater 'i9 through line 80 to separator 6Iwhere the sludge separates from the propane and is withdrawn throughvalve 82 and sent through line 83 to storage 84. The propane vapor isvwithdrawn from separator 8| through line 85 to compressor |I2 where itis compressed and vsent by means of line 88'to condenser 89 where it isliqueed and sent by means of line I I 0 to separator 90 where it isseparated from any liquid sulphur dioxide and sent by means of valve 9|,pump 93, line 96 to storage tank I0. The liquid sulphur dioxide inseparator 90 is withdrawn through valve 92 and sent by pump 94 tosulphur dioxide storage tank 42.

The acid treated oil in separator 10, dissolved in propane carryingvarying amounts of sulphur dioxide, is withdrawn through line 1| andpassed through clay tower 12 where any remaining solution is separatedout. The fraction of oil leaving clay tower 12 passes by means of line13 to evaporator 'I4 Where the propane and sulphur dioxide present arevaporized Iby aid of steam introduced through closed coil 91 and aresent by means of line 86 to compressor 81 where they are compressed andsent by means of line 88 to condenser 89 where they are liqueed and sentby means of line I I0 to separator 90. Liquid propane in separator 90 isreturned to storage tank I0 through valve 9|, pump 93, and line 96. Thesulphur dioxide in separator 90 is returned to storage tank 42 throughvalve 92, pump 94 and line 95. The oil in evaporator 14 which is freefrom propane and sulphur dioxide is removed through valve 98 and sent bymeans of line 99 to refined oil tank |00.

As illustrative of the operation of our process for one type of oil andWithout intending to limit our invention, water free residual oil intank l of the figure at a temperature of about 200 F. is mixed withliquid propane and cooled by allowing a portion of ,the propane tovaporize under reduced pressure until the temperature of the topped oiland propane is about 120 F. after which it is thoroughly mixed inagitator I4. The thoroughly agitated mass is then passed into decanterI6 where the propane solution of lubricating oil and Wax is separatedfrom the undssolved asphalt. This oil dissolved in liquid propanecontains a mixture of paraffinoid and non-paramiloid components. Bysubjecting this mixture to the selective solvent action of liquidsulphur dioxide in the presence of liquid propane it is possible toresolve the mixture into a portion of a non-parafnoid nature soluble inliquid sulphur dioxide and a portion of a paraffinoid nature soluble inliquid propane. The Wax present in the mixture being more soluble in theliquid propane than in the liquid sulphur dioxide remains in solution inthe former. This mixture of paraflinoid oil and Wax dissolved in liquidpropane is then chilled to a point suiiicient to cause precipitation ofthe wax, after which the chilled mass is filtered, centrifuged or coldsettled to remove the wax. 'I he wax-free solution of parainnoid oildissolved in the liquid propane is then treated with sulphuric acid toremove further undesirable bodies present, after which the solutionformed is settled out and the propane removed by distillation from therened oil.

The foregoing exemplary description is merely illustrative of apreferred mode of carrying out our invention and is not to Abe taken aslimiting, as many variations may be made within the scope of thefollowing claims by a person skilled in the art Without departing fromthe spirit thereof.

We claim:

, l. A process for the production of lubricating oil from oil containingwax which comprises commingling said oil with a liquid having aselective solvent action as between parainic and nonparaflinic fractionsof the oil and a relatively less selective solvent liquid to form anextract' phase comprising selective solvent and non-paralnic fractionsand a raffinate Phase comprising selective solvent, less selectivesolvent and parafnic fractions including wax, separating said phases,cooling the raffinate phase to separate wax and removing the wax fromthe raffinate phase.

2. A process for the separation of mineral oil into fractions comprisingcommingling said oil with a selective solvent as between paranic andnon-paraiiinic constituents of the oil, and ethyl ether to form araffinate phase comprising paraffinic constituents of the oil and etherand an extract phase comprising non-parafnic constituents of the oil andselective solvent, and separating said phases.

3. In the manufacture of lubricating oil from mixed base mineral oil,the method of separating therefrom fractions of differing viscosityindex comprising extracting the oil with a solvent having a selectiveaction substantially of the character of that of sulphur'dioxide as'between said constituents of differing viscosity index, in the presenceof ethyl ether, said solvents being adapted to form a 2-layer liquidsystem with the oil whereby the oil is separated into fractionsrespectively rich in low viscosity index and high viscosity indexconstituents.

4. The process of manufacturing low cold test high viscosity indexlubricating oil from Waxbearing mineral oil which comprises mixing theoil with liquid sulphurdioxide and a modifying solvent having relativelyless selective action than sulphur dioxide as between low and highviscosity index constituents of the oil, in such proportions with theoil that the mixture exerts a selective solvent action as between therelatively low viscosity index constituents and the relatively highviscosity index constituents including wax, forming an extract phasecomprising low viscosity index constituents and a raffinate phasecomprising high viscosity index constituents and wax. separating theextract phase from the raffinate phase, chilling the raffinate phase andseparating the Wax hydrocarbons from said chilled raffinate phase.

ULRIC B. BRAY. CLAUDE E. SWIFT.

